The present invention is directed to reed valves. More specifically, the present invention is directed to the design and construction of the elements of a reed valve.
Reed valves are simple, high performance one-way valves which can be used in a variety of contexts. They have recently been employed with substantial success in two-stroke engine design. High performance two-stroke engines such as employed on motorcycles have been developed which employ a reed valve in performing at least part of the valving function more traditionally performed solely by porting in the engine cylinder. As combusting gases are not required to pass through such valves, and as high r.p.m. requirements are needed, the reed valve has been found to be well suited to two-stroke engine design.
The traditional reed valve as employed on internal combustion engines is illustrated, for purposes of explanation, in FIGS. 17, 18, and 19 herein. Considering the problems of heat-resistance, corrosion resistance, wear resistance, etc., reed valves 10 have been generally formed from flat plates of stainless steel material or its equivalent. This plate is attached at its base end with one or more fasteners 12 to a valve port 14 located through the body of the reed valve system with which the valve is associated.
The reed valve 10 acts as a check valve because the valve element extends beyond the rim of the port 14 as can best be seen in FIG. 18. In the context of an engine, the carburetor and intake assembly would be to the right of the valve 10 while the left side is associated with the air-fuel mixture compression chamber. The valve operates on differential pressure, primarily induced by the creation of vacuum on the left side of the valve as it is shown in FIG. 18. As two-stroke engines are expected to run at relatively high speeds, the valve must open and close very rapidly with each revolution of the engine. During compression of the air fuel mixture in the compression cavity, the valve 10 must move to the right as seen in FIG. 18 to prevent mixture from escaping through the carburetor. During charging of the compression chamber of the engine, the valve 10 must move to the left, off the seat, so that air-fuel mixture may flow into the engine.
The performance required of such reed valves creates problems associated with both the structure and the operation of these devices. In order to achieve quick, responsive movement, the valve must be light. It must also exhibit the appropriate spring rate, be resistant to corrosion, be strong enough to withstand the gas pressures experienced and withstand the repeated vibration of its operation. One specific difficulty which can develop is that the satisfaction of certain other of the requirements listed results in the valve operating in a engine speed range which includes the natural frequency of the valve. A resonance can develop which results in the independent vibration of the reed valve. Such resonance in turn results in the imperfect seating of the valve and improper movement not in time with the engine. As a consequence, engine output can be adversely affected. Also, the structural integrity of the reed valve itself may be detrimentally affected.
The repetitive vibrational movement, whether caused by resonance or simply repeated gas pressure loads, can result in fatigue failure of the reed valve when thin walled construction is applied as a possible solution to certain performance requirements. Consequently, thin walled construction has been avoided because of the resulting problems with tearing of the valve material, etc. As a result of the foregoing difficulties, the relatively simple reed valve has found difficulty in providing satisfactory performance in high-speed, two-stroke engines.